Jo Eglen, founder of Little Hen Rescue, in Flordon, near Newton Flotman, said the attack in the early hours of yesterday morning could be the final straw which forces the centre to shut for good.

In recent years, Little Hen has arranged for a nightwatchman to stay on the Greenways Lane site overnight in an effort to deter thieves, who have targeted the centre on previous occasions.

However, at about 3am, three masked men broke into the caravan where Toby Chaplin, 23, was staying.

They bound him with parcel tape and punched him, before making off with items including a laptop, stereo, mobile phone, and a vacuum cleaner. No birds or animals were harmed.

The shop, after the robbery.

Mrs Eglen, who founded the centre in July 2008, said Mr Chaplin, a part-time nursery nurse who has been with the centre for a year, was “all right”, but had a swollen face and a black eye.

She said: “It feels like the final straw. I have had it. I can’t protect my animals or protect someone there who I thought would be OK.

“He is only a lad and I feel so guilty that he was there and they did this to him. I thought the deterrent was enough. It just feels that I’m at a place where my animals are not safe. Although they did not go for the animals, they did the time before.”

The centre re-homes chickens with families around Norfolk and Suffolk, saving them from slaughter at the end of their commercial life with egg farms.

Mrs Eglen said Mr Chaplin told her that during the raid, which may have lasted about one hour, he had been more concerned about the safety of the animals than himself.

She said the robbers had rummaged through chicken medicine, stealing needles and syringes, and also took Mr Chaplin’s phone and the lights from his bike.

Investigating officer Sarah Knights, from Norwich CID, said: “While the investigation is in the early stages, our inquiries are focused on this being a targeted incident as opposed to a random attack.

“We are also exploring the possibility of links with a similar incident in Wymondham at the end of July.”

Anyone who saw three men acting suspiciously in the area at this time should contact DS Knights at Norwich CID on 101 or call Crimestoppers anonymously on 0800 555 111.